In recent years, the technology to treat the skin has been widely applied to methods of changing or removing states of skin tissues by radiating light. Therefore, the optical apparatus for skin treatment is developed using various types of electromagnetic radiations such as a laser beam, a flash lamp, RF frequency, a microwave, an ultrasound and the like.
If the light is radiated using the optical apparatus for skin treatment, the light with a specific wavelength may be penetrated to the inside of the skin, and may be absorbed into the various tissues such as collagen, hair follicles, and hemoglobin located on the inside of the skin according to the wavelength characteristics. In addition, the absorbed light is converted into thermal energy in the tissue to change a state of the tissue by applying thermal damage to the tissue.
At this time, the skin surface is typically cooled before the light is radiated or while the light is radiated, since it may cause damage on the skin surface by the thermal energy generated during radiating the light. For example, the skin is cooled by a refrigerant or heat transfer device in which the skin is in contacted with a thermal conductivity member to maintain a low temperature, or a method for cooling the skin is mainly used in which the cooling gas of an extremely low temperature is sprayed onto the skin surface. Thus, the treatment of the internal tissue of the skin is achieved in a state where the surface of the skin is maintained at the low temperature when the light is radiated.
However, if the treatment is processed in a state where the skin surface is cooled as in the prior art, there is a problem in that it may cause damage on the skin surface when the light is radiated as output of more than a certain size. Thus, there was a limit to process the treatment by supplying the sufficient thermal energy to the skin tissue.
Furthermore, when the treatment of removing a capillary vessel located on the skin surface is performed, if the skin surface is cooled as in the prior art, a phenomenon that the capillary vessel is contracted and disappeared from the skin surface can be observed. As such, in a case of some lesions, when the skin surface is cooled, since the temperature of skin surface is rapidly decreased and the lesion is temporarily disappeared, there is a problem difficult to treat by radiating the light onto the correct location after cooling the skin.